Relatively rigid frames used to house various kinds of components are known in the art. For example, rectangular-shaped, three-dimensional frames are often used to house an air filter media in a central heating, ventilating and air conditioning (HVAC) system in a residence or other building. It is advantageous to ship such filter frames in pieces (i.e., in a “knockdown” configuration) so that they can assembled on site by an installer. However, assembly of such frames on site may require as many as 16 fasteners (four in each corner), which adds to the expense and time of assembly.